The `pose_bone_do_paste()` function is documented to only return a
non-NULL pointer on a successful paste, and the one caller that checks
the return value is expecting this behaviour. However, before this
commit, when a valid pose channel was found, 'Selected Only' was
enabled, and the bone was not selected, the function would still return
non-NULL. This resulted in auto-keying pose channels that were not
pasted.
Reviewed by: angavrilov
Differential Revision: https://developer.blender.org/D5891
1ca5c8491d